DE69628627T2 - Extrusion die for honeycomb structure and process for its manufacture - Google Patents

Description

BACKGROUND THE INVENTION

The present invention relates on improved forms for the extrusion of honeycomb Structures made of plasticized organic or inorganic batch materials. The invention relates in particular to a honeycomb extrusion head, which is a laminated transition area for improved head performance and durability as well as procedures for Manufacture and use of this head contains.

The use of extrusion heads for education of honeycomb Structures with thin walls well known. U.S. Patent Numbers 3,790,654 and 3,905,743 (Bagley ) describe a construction for such a head, which contains a plurality of feed openings, which through a filling surface of the Head and through the head body run to extrudable material to a laxation area to transport, which is formed on the outlet side of the head by a series of discharge slots becomes. The discharge slots are connected and form the extrudable material in the course of the removal from the drain side of the head into a structure with each other connected walls for one honeycomb body with channel.

To the same extent as the use of such honeycomb Structures has increased, so has the demand for extrusion heads, which capable finer structured honeycombs are to be formed. A fundamental limitation of this Heads is however, the fact that neither the feed openings nor the discharge slots can be multiplied indefinitely, because they are plastic coated Powder extrusion used extrusion pressures considerable Stiffness or toughness in the Need head to avoid distorting or breaking the head.

One approach to this difficulty The so-called compound feed head construction is to be corrected. At this Construction consists of the filling area of the Head of two or more plates with holes a thick, stiff first or layer filler plate which has relatively large feed openings contains which is a second or inner plate, which is a series of finer feed openings contains supply with the extrudable batch. The inner plate conducts the batch material on to the discharge slots on the discharge side Of the head. U.S. U.S. Patent Nos. 4,118,456 and 4,321,025 this kind of head while U.S. U.S. Patent No. 4,465,454 the use of an overlapping arrangement of the two sizes of feed openings Disclosed to prevent flow restriction inside the heads.

Variations of the compound feed head contain those in U.S. No. 4,243,370, wherein Guiding channels for management the extrudable material is available in the discharge area of the head, U.S. U.S. Patent No. 4,298,564 describes a similar head configuration wherein a combination of guide slots and flow restrictions is used to control the distribution of the extrudable Material on the discharge surface of the Head to improve.

The development of minds has also focuses on means a more uniform flow and one correct distribution of the extrudable material to the drainage surface of the Head. Applications 52-8761 and 52-8762 of Published Japanese utility models, for example, describe discrete channels for distribution of feed streams directly Slits on the drain surface, while U.S. U.S. Patent No. 4,242,075 describes a head construction with feed material distribution channels, which is a series of spoke-based cell blocks for formation which feeds cells in the extruded honeycomb.

Technology has long recognized its appeal the feed channels in one Smooth the extrusion head, to reduce back pressure and head rubbing to diminish which by the inorganic powder mixtures which extrudes be evoked. U.S. U.S. Patent No. 5,066,215 a head in which the feed openings uniform to discharge slots on the top drain surface taper to a point. U.S. U.S. Patent No. 3,846,197 describes a similar one gradual transition of the feed openings and discharge slots, wherein the head in this case by stacking a large number is assembled on glass plates. Each of the plates is at least partially etched, to the desired one Row of feed openings or discharge slots to create and the head body will then by stacking the etched ones Plate and heat this to make the layers of glass integral Merge unity, put together.

Despite the previous developments current extrusion head manufacturing processes are still based on drilling of feed openings in an area a metal head body instructed while discharge slots in the opposite area get cut. The manufacturing processes currently used for the production of honeycomb extrusion heads disadvantageously use conventional ones rotating or straight tools. Even the electrochemical Machining and wire erosion are largely incapable of being complicated Contours inside these heads to accomplish.

As can be seen from a study of this manufacturing technology, the depths of the feed openings and discharge slots are normally checked precisely in order to form the desired overlap dimension for the correct distribution of an extrudable batch material to the slots on the discharge surface. However, since the Be area of the feed opening / slot overlap is formed within the inaccessible interior of the head, it rarely, if ever, creates an effective flow path. In contrast, studies of the inner areas of the heads used for ceramic extrusion consistently show that powdered batch materials do not find the overlap area which is primarily intended to be smoothed, but instead tend to wear the inside of the head in a changed and relatively complex configuration , which is apparently more conductive to the efficient charge flow.

The problem of a batch material from a feed port inlet to a discharge slot drain without any problems to transport can be better understood if it is recognized that the batch flow is longitudinal the feed opening area of the head but very much at the feed opening / discharge slot interface quickly changes to a combination of a transverse and longitudinal flow. A fast cross flow at these connections is needed around the discharge slot row enough to fill but if the flow is not uniform it will be extruded Product defects, such as B. the growth of the cell walls on the edge, wavy or thick cell walls, missing cell walls and clogged cells.

Given these ongoing difficulties It is a primary object of the present invention to provide an extrusion head to create which many of the extrusion heads produced by conventionally Addressing problems more effectively.

Another object of the invention is to provide an extrusion process in which an improved Head is used, which extruded honeycomb with an improved Shape and quality at reduced extrusion pressures supplies.

Other tasks and benefits of Invention will become apparent from the following description of these become.

SUMMARY OF THE INVENTION

In relation to the present invention will address the problem of material flow control at the feed opening / slot interface honeycomb Extrusion head by forming the interface from a stack thinner Plates tackled. Each plate in the stack will have multiple openings included, which is a very thin Cross section of the desired Represent the river channel within the head at this point.

This approach allows each successive Plate in the stack their own unique geometry or outer shape to have. Usually this geometry will be slightly different than the adjacent plates in the stack to make a desired flow change to achieve. Alternatively, you can two or more successive plates have the same opening geometry for the purpose of supply flow compensation or for other purposes. Among the river changes, which are caused by a multilayered interface of this type extrudable in flow streams Material can be effected are the subdivision or merging of the river currents, changes in the flow direction, changes in the form of the river currents and increases or Decreases in the flow rate. The latter usually arises from a compression or expansion of the river currents.

In many cases, these flow parameters can be independent of each other changed become; in other cases they are interdependent. In any case, the ability the river currents from each feed opening or to divide in order to create a large number of side streams, particularly Meaning, since such a merger is a wide but precise one Redistribution of extrudable material from a relatively small amount Number of feed openings guarantee can. Thus, the flow form of the material with which each is chosen arbitrarily Rbführschlitz configuration series should be optimized without the number of the feed openings in the filling or feeding raise the head to have to.

In a first aspect, the invention then creates a honeycomb-shaped extrusion head which comprises the following:
a feed area with a plurality of feed openings for filling an extrudable material;
a discharge area which ends at a discharge surface, the discharge surface comprising a discharge opening for discharging the extrudable material in the form of a honeycomb-shaped body with channels; and
a transition area which is arranged between the supply and return guide area, characterized in that the transition area is formed from a stack of at least four interconnected metal transition plates, each plate having a sheet thickness of less than approximately 1 mm, and the transition area a plurality on channels, which are formed by succession of openings in the transition plates, for conveying the extrudable material in the form of a feed stream between the feed and discharge area.

The plates thus form a succession of openings which align to form uninterrupted transition channels for the conveyance of extrudable material from the feed openings to the discharge area of the head. The transport takes place in multiple feed streams and these can be combined (divided) and / or regulated in terms of size, shape and direction. In this way, the large, sudden changes in flow direction and flow speed, which one encounters with conventional heads, can be avoided and significant mindset Reductions in head impedance and / or head wear can be achieved.

• (i) das Zuführen eines extrudierbaren Materials in Form von einer Vielzahl an Zuführströmen in eine Vielzahl an Zuführöffnungen, welche in einen Zuführbereich eines wabenförmigen Extrusionskopfes verlaufen;
• (ii) das Weiterleiten der Zuführströme von den Zuführöffnungen in einen mehrschichtigen Übergangsbereich, welcher an den Zuführbereich angrenzt, wobei der Übergangsbereich mindestens vier miteinander verbundene Metallübergangsplatten umfasst, wobei jede Platte eine Blechstärke von weniger als ca. 1 mm hat und eine Vielzahl an Kanälen, welche durch Aufeinanderfolgen von Öffnungen in den Platten gebildet wurden und zur Beförderung der Zuführströme mit den Zuführöffnungen verbunden sind;
• (iii) das Zurückführen, Umformen und/oder Teilen der Zuführströme innerhalb der Kanäle im Übergangsbereich, um eine Vielzahl an zurückgeführten, umgeformten und/oder geteilten Zuführströmen aus extrudierbarem Material zu stellen;
• (iv) das Weiterleiten der zurückgeführten, geteilten und/oder umgeformten Zuführströme vom Übergangsbereich in einen Abführbereich, welcher an den Übergangsbereich angrenzt, wobei der Abführbereich eine Abführöffnung umfasst, welche mit den Kanälen verbunden ist und zum Abführen des extrudierbaren Materials in Form eines wabenförmigen Körpers mit Kanälen konfiguriert ist; und
• (v) das Abführen des extrudierbaren Materials von der Abführöffnung in Form eines wabenförmigen Produktes.

In another aspect, the invention provides a method for extruding a honeycomb product, which comprises:

• (i) feeding an extrudable material in the form of a plurality of feed streams into a plurality of feed openings which run into a feed area of a honeycomb extrusion head;
• (ii) routing the feed streams from the feed openings into a multi-layer transition area which is adjacent to the feed area, the transition area comprising at least four interconnected metal transition plates, each plate having a sheet thickness of less than approx. 1 mm and a plurality of channels, which have been formed by succession of openings in the plates and are connected to the supply openings for conveying the feed streams;
• (iii) returning, reshaping and / or dividing the feed streams within the channels in the transition area to provide a plurality of returned, reshaped and / or split feed streams of extrudable material;
• (iv) routing the recycled, split and / or reshaped feed streams from the transition area to a discharge area adjacent to the transition area, the discharge area including a discharge opening connected to the channels and for discharging the extrudable material in the form of a honeycomb body is configured with channels; and
• (v) discharging the extrudable material from the discharge opening in the form of a honeycomb product.

In particularly preferred embodiments The invention uses the extrusion head and the extrusion process a transition area which every feed stream in at least two and most commonly in 3-16 secondary streams brings together or share. The merge can executed once become, d. H. in a single step, or two or more Paint in a second step or subsequent merge steps. In the areas of the transition channels, which the merging Layers or sections in the transition area separate, the reshaping and recycling of the secondary flows is either in preparation for the subsequent merge steps or carried out for forwarding to the discharge area of the head.

In yet another aspect, the invention provides a method of making a honeycomb extrusion head which comprises the steps of:
Forming a plurality of feed openings in a nozzle plate;
Forming a series of openings in each of at least four interconnected metal transition plates, each plate having a sheet thickness of less than about 1 mm;
Stacking the transition plates to form a stack of plates, wherein the openings in each plate are at least partially overlapped with the openings of adjacent plates in the stack of plates, and wherein the arrangements of the openings form a series of channels through the stack of plates;
Positioning the plate stack against the nozzle plate so that the feed openings are at least partially overlapped with the channels;
Positioning a mold removal area against the plate stack; and
Connect the die plate to the plate stack and die removal area to form a preform of the extrusion head.

The mold discharge area can be a series of pins include their gaps comprise a discharge opening or can comprise a discharge opening or can comprise a flat plate, which is then joined with provided a discharge opening can be. The nozzle plate, transition plates and the discharge area arranged in this way are then joined together to form a whole, connected extrusion head preform to build.

If the head discharge area is a flat plate comprises a discharge opening is formed in the plate after the connection which are with the channels in the transition area communicates. This opening will be configured extrudable material made by the channels was supplied in the form of a honeycomb body with channels. If the laxation area is a row of pins, the row of pins is configured and positioned to be an effective filling the pin spaces with extrudable material, which from the channels in the discharge area arrives.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is further referenced described in the drawings in which:

1 is a schematic, isometric partial view of an extrusion head in cross section, which was manufactured according to the prior art;

2 Figure 3 is a schematic, isometric, partial cross-sectional view of a head made in accordance with the invention;

3 Fig. 3 is an exploded view showing the components and structure of a head of the invention;

4 Figure 14 shows a course of predetermined shapes for the channels with which each of a plurality of transition plates for a transition region is provided in a head of the invention;

4a is a schematic plan view of a transition region channel, which by the channel shapes of the 4 was delivered;

5 shows an alternative course of molds for the channels with which a row of transition plates for a mold according to the invention is to be provided; and

6a and 6b are schematic top views of the first and second portions of a merging transition channel for a head of the invention.

DETAILED DESCRIPTION

A comparison of the internal structures of a conventional extrusion head or an extrusion die and a head according to the invention is shown in FIGS 1 and 2 of the drawings. 1 Fig. 3 is an enlarged, schematic, isometric partial view of a prior art head, not in true proportions or to scale, showing the die removal area and a portion of the adjacent nozzle plate area of the head in increased cross-section. The view was taken to best show the transition zone between the feed openings in the head body and the discharge slots which form the discharge opening of the head.

In particular on 1 related, the extrusion head shown is formed by machining a metal block, which is partially as 12 will be shown. feed openings 13 to fill extrudable material into the head are first by drilling into the bottom (not shown) of the block 12 and then discharge slots are formed 17 in the top surface or discharge surface 18 cut the block to cross the feed openings. The slots 17 provide discharge openings, of which batch material, which the feed openings 13 crosses from the surface 18 can be dissipated as a honeycomb structure.

One difficulty with this head design is that the connections or transitions that go through the surfaces 15 are shown between the feed openings 13 and the discharge slots 17 are unequal. That is, it is difficult the surfaces 15 with an equal smoothness and shape and that these can often contribute to river interruptions, which can introduce discontinuities in the walls of the extruded honeycomb.

In addition, the surfaces 15 Areas of very high wear in these heads, since the batch material has to change direction, for example from one with the feed openings 13 parallel flow axis in a combination of forward and lateral flows in the discharge slots 17 , A sideways flow in the slots 17 is required so that the batch material when exiting the area 18 of the head in an uninterrupted honeycomb wall structure.

2 of the drawings shows an enlarged, schematic, isometric partial view, again in side cross-sectional view, of a portion of an extrusion head containing a multi-layer transition region according to the invention. The head 20 in 2 consists of a base area 22 , a laxation area 26 and a transition area 24 , The base area or nozzle plate area 22 contains feed openings 23 while the laxation area 26 discharge slots 27 contains which on the discharge surface 28 end up.

The multi-layered transition area 24 is between the base 22 and the laxation area 26 arranged and provides the connecting channels 29a - 29b which ensure the smooth distribution and delivery of the batch material from the feed openings 23 to the discharge slots 27 are necessary. In this header illustration shown, which is intended to be illustrative and not restrictive, the channels 29a - 29b through the stack of thin plates 25a - 25j educated. The channels formed by this stack are configured around the feed streams from the feed openings 23 for forwarding into the discharge slots 27 to both share and reshape.

channel regions 29a start at the base transition plate 25a ¹ and lead from the feed opening ends to the feed opening area 22 path. The division of the feed streams is effected because there are channels 29a on the transition plate 25f in secondary channels 29b divide or branch. Only two of the four secondary channels 29b which of each channel 29a can branch off in the through 2 posed view can be seen.

Feed current transformation within the head 20 is achieved because of the shape of the secondary channels 29b in cross-section from an almost round at the channel division point to a rounded rectangular shape at their outlets from the end transition plate 25j changed. Thus, a large part of the laterally directed (slot-wise) flow of the batch material required to fill the discharge slots is the batch material from the secondary channels before discharge 29b available.

3 of the drawings is an exploded, enlarged, partial schematic view showing the components of the head and the construction of a preform for a head provided in accordance with the invention. As in 3 shown is the nozzle plate 32 which with feed openings 33 was used as a base on which thin plates 35a - 35d which comprise the plates of the transition area of the head and the discharge area 36 are arranged.

In the component arrangement shown, which illustrates the parts required for a head with a four-layer transition region, each of the transition plates is 35a - 35d with a row of openings 39a - 39d predetermined cross shape. The configuration of the openings in the succession of plates is designed to match the channel shapes created by the sheets from the circular configuration of the feed openings 33 were formed to modulate cross shapes, which are the intermediate areas between themselves in the discharge area 36 of the construction intersecting discharge slots 37 correspond more.

In particular on 3 are in the row of openings 39a in the first or base transition plate 35a the openings the circular configurations of the feed openings 33 in the head body 32 similar. The openings 39d in the last or end discharge plate 35d are configured to define the slot gaps created by the intersecting slots 37 were formed to supply batch feed streams with a cruciform configuration.

In the in 3 The illustration shown was the formation of the discharge slots 37 in the plate 36 not yet completed. Instead, the discharge slots run 37 only partially into the plate, which ends at a collective, flat boundary, which is shown by the dashed line 36a along the edge of the plate 36 is shown. The through line 36a the displayed plane is also parallel, but is at a distance from the continuous surface of the plate 36 opposite the slotted plate surface.

The material layer without slits over the line 36a in plate 36 serves as a supporting surface or membrane for the "pins" 37a formed by the intersecting slots in the machined surface of the plate. This layer maintains and maintains the axiality and spacing of the pins 37a , because the components in 3 assembled and joined together to form a uniform head preform.

In the assembly process and when connecting the components in 3 , are the transition plates 35a - 35d in a stack with the surface of the nozzle plate 32 connected and the ends of the pins 37a in the partially slotted plate 36 are connected to the top transition plate in the stack. A connected structure is thus formed which corresponds to that in 2 resembles, except that it has vent slots 37 which are not yet open for removal.

In order to provide the necessary discharge opening in this structure, the slots 37 after joining by an additional slot step or preferably by removing the base or membrane material above the dashed line on the plate 36 open.

Through the course of the transition plates 35a - 35d in the after 3 formed head, a significant lateral redistribution of the batch material in the transition area is effected around the discharge slots 37 to fill. Because this redistribution the feed streams are not only to the sides of the pins 37a conducts as in 2 , the head of 3 the amount of laterally directed batch flow that is required in the slots is still considerable. In addition, reshaping the feed streams to more closely match the configuration of the slot spaces significantly reduces the degree of wear due to the batch material at the corners of the pins 37a ,

In an alternative method of manufacturing a head preform, not in 3 illustrated, the plate shown under construction is shown 36 replaced by a surface or discharge plate without openings. After this plate has been connected to the other components of the structure, discharge slots or other discharge openings are formed in the unprotected side of the discharge plate by conventional sawing, machining by spark erosion or other machining methods. However, because of the material deformation that occurs during the connection, it is considerably more difficult to achieve an optimal axiality of the preformed transition channels with the discharge slots machined after the connection than with the discharge slots formed before the connection. Therefore, for best slot axiality with the channels in the transition area and also with slots with complex cross sections, as in 3 shown, preferred the use of a previously slotted cover for the head discharge area, as shown in this figure.

Any of the known slot methods can be applied to slots, such as the slots 37 in the discharge area as in 3 shown head to form and / or to complete. Examples of such processes are spark erosion and precision saws. However, the currently preferred slot method for honeycomb extrusion heads made as described is grinding wheel grinding. When using a tooling such as a small, thin boron (cubic boron nitride) grinding wheel, grinding wheel grinding offers special advantages in terms of low costs, high speed and good finishing of the slot side walls. In addition, it is particularly suitable for the formation of slots twice as wide 37 , as in 3 shown.

In the same way, any of the well-known hole drilling methods can be used to form the series of supply openings in the nozzle plate area or supply opening area of the head. Particularly suitable processes include deep drilling and electrochemical machining processes. Since the nozzle plate consists of through holes and not those in conventional heads, as in 1 shown, blind holes used, secondary bushings, such. B. honing or other opening smoothing, advantageously be easily applied to improve the smoothness and uniformity of the feed openings if necessary.

The composition, number and strength of the thin Plates or sheets that are used around the interface area of the extrusion head of the invention will be selected that they meet the demands the special extrusion application for which the head is intended equivalent. In general, however, it is desirable that panel thicknesses and opening shapes be selected about very quick changes in channel size, shape or flow direction from plate to plate. The transition area in these heads can be useful be considered to have the direction of the batch flow in a Sequence of steps changes through the slabs arose in the stack. The thinner the slabs used are the smaller the stairs and the smoother becomes the river crossing his. Size directional changes are limited by the opening dislocations avoided from plate to plate, the opening offset using the Angle between the opening centers is measured in adjacent plates. The number of plates will selected, by the cost of an increasing plate size against the standard, which is above the Feed flow is desired auszuwägen.

The row of openings in each of the thin plates, which are used for the transition area of the head can be constructed by conventional Machining processes are formed, but more suitable series will be made by photochemical processing. By means of this Known, mature methods can be used in a flexible and plates with etched openings can be produced economically.

As suggested in the previous description, are the multilayered transition heads of the Invention very effective in flow sharing or shaping functions of flux return functions. That is, any river return, river division and / or flow forming can be carried out optimally, almost without taking the others. For example the starting plates in a stack of plates a feed stream divide into four smaller feed streams, which leads to the four sides of a four-sided cell head should be while the plate stack at the same point or downstream from Point of division the shape and / or volume of each smaller flow such as can change desired. Thus, a circular Secondary flow into a secondary flow with an elongated or rectilinear cross section be reshaped to the discharge slot to better match the head to which it is to supply.

The most effective configuration for the transition area from the standpoint of reduced flow impedance is one in which the River axis for the extrudable material within the transition area not from the longitudinal direction of the batch flow through the feed openings and from the discharge surface an angle greater than deviates about 30 degrees at any point along its length. By reasonable Selection of the transitional Layers of the laminated transition area of the Head very few layers, for example 5-10 layers, are used, for effective repatriation and / or Division of the feed flow without crossing this limit.

On the other hand, many more layers, for example 10-50 or even 100 layers, used to cover the walls of the transition area to "smooth". Such smoothing can in some cases be advantageous to the feed streams or secondary streams attributed or to reshape while at the same time, batch accumulation points or "dead spots" in the finely structured channels are reduced or essentially be eliminated.

The use of multiple transition plates normally closes the use of thinner Plates with one, compatible with the task of reducing the size of the "steps" in order to to smooth the transition channels. The thicknesses however, are even in minds with small plate size, in general 0.0508 cm (0.020 inches) (500 μm) do not exceed and are usually 0.0127-0.0254 cm (0.005-0.010 inches) (125-250 µm) thick. In principle, plates up to 0.00508 cm (0.002 inches) (50 μm) or even less can are used, especially when tighter construction tolerances and an improved vertical position is required for apertured side walls, despite something higher Costs.

In the channel construction of the 3 the feed streams were reconfigured but not divided. 4 illustrates a course of opening shapes (enlarged) for a transition channel construction, which is more the construction in 2 corresponds in which the channels both split and reshape the feed streams.

A transition area of the channel construction of the 4 would contain 6 Transition plates included, each subsequent plate, which contains a series of openings, formally one of the shapes in the in 4 corresponds to the series of shapes shown. The plate, which has a series of openings of the shape 49 (a) in 4 contains, would split each batch stream from the feed ports in an adjacent feed port area into four bypass streams. As a result, the openings of the molds 49 (b) - 49 (f) Form each side stream into an elongated cross-section, as would be suitable for extrusion into the base of a slot segment section in the discharge area of a honeycomb-shaped extrusion head with square cells.

Panels with the opening shapes from 4 would, when stacked in a multi-layered transition region, form a channel, as schematically shown in the enlarged top view of FIG 4a shown. 4a compares the size and shape 43 a feed opening, which in a head base plate with the openings in a stack of superimposed transition plates, which as in 4 shown shaped opens.

The in 4a Shown form comparison illustrates the manner in which, with the overlap of the transition plate openings, the overlapping opening shapes of the 4 Would provide channels, which are of shape 49 (a) (The shape and size of the feed opening fits closely 43 ) to the extended form 49 (f) (which corresponds approximately in shape and size to a discharge slot segment). Likewise, angling the divided channels away from the flow axis of the feed opening 43 proposed, the latter being perpendicular to the plane of the drawing. The angles between the flow axis of the feed opening and that of the channels can be calculated from the thickness of the transition plates and the displacements in the opening positions from each transition plate to the next.

A construction of the transition area for an extrusion head for a honeycomb extrusion with triangular cells is shown in 5 of the drawings. The shape of the shapes in this figure was designed to provide a channel for dividing, reshaping, and returning a single circular feed stream into three elongated feed streams that feed extrudable material evenly around a triangular "pin" in the discharge surface of such a head. As in With this construction it can be seen that the subdivision of each feed stream of the feed openings takes place in the transition area, which is the channel shape 59 (b) has, but the reshaping of all three resulting feeder sidestreams occurs over the course of the shape 59 (c) to 59 (j) ,

Merging or dividing a stream of extrudable material from a feed opening of the head, as previously noted, can be performed multiple times and in multiple sections of a single transition area in these heads. A channel construction for a two-stage merging is shown schematically in the 6a and 6b of the drawings. In 6a , corresponding to the first merging step, a feed stream from a circular feed opening 63 in an initial transition plate of the channel shape 69 (a) divided into four sidestreams, and each of the four sidestreams is then over the course of the channels 69 (b) - 69 (g) formed into a symmetrical, octagonal cross-sectional shape.

In the second merge step, in 6b shown, each octagonal side stream is from the opening 69 (g) in the first merge step the 6a in a transition layer with openings of the form 69 (h) divided into four smaller side streams. After that, each of the smaller side streams is over the course of the channel openings, starting with channel shape 69 (i) and ending with channel shape 69 (k) , transformed into elongated flow forms which are suitable for the uniform supply of extrudable material to the slot sections of a honeycomb-shaped extrusion head with square cells. The distinct advantage of this multiple merge approach is that four cells of an extruded honeycomb product from a single feed opening 63 can be completely formed in a nozzle plate. This dramatically reduces the number of feed openings required to manufacture fine structure honeycombs.

Assembling the nozzle plate, transition area plates and Abführbereichplatte the heads, as shown in the drawings, to a preform for one finished extrusion head according to the invention can by application conventional Fastening or Connection procedure for Metal performed become. In principle, could any assembly process, including soldering and brazing or even mechanical fastening can be applied, but the preferred one The method of assembly is the diffusion contact production. The the latter method forms an entire head structure, which is easily the Strength and the target of the size, which for fine structured extrusion heads are needed.

U.S. Patent No. 3,678,570 (Paulonis and others) describes a suitable diffusion contact manufacturing process, especially for Superalloy and stainless steel compounds suitable, wherein thin intermediate layers from alloys are used to make the diffusion contact making process through the formation of a temporary liquid Support phase. Promote these intermediate layers good diffusion contacting of similar materials at temperatures and pressing, which is slightly below that for conventional diffusion processes benötigtem Range.

The invention is further referenced explained on the following example which are illustrative and not restrictive should.

example

Components for the feed, transition and discharge areas for a honeycomb extrusion head are selected first. The feed area consists of a nozzle plate, which is composed of stainless steel of type 422 PM (steel of type 422 compressed from steel powder). This plate is deep drilled to provide a row of feed openings consisting of approximately 16 openings / cm ² (100 openings / in ² ) of the plate surface. The surfaces of the plate are then ground and polished to create a finished nozzle plate with a series of smooth through holes.

The transition area of the extrusion head is made up of a stack of six thin plates stainless steel. Each plate has a thickness of approximately 0.250 mm (0.010 in) and is made of type 410 stainless steel. The openings in the transition plates are formed by selective etching using conventional photochemical processing methods. Each plate is machined to provide an opening row in which the opening groups are provided with a shape which is substantially in accordance with another shape of the opening shapes 49a - 49f is which in 4 of the drawings are illustrated. Plate (a) contains openings which essentially correspond in number and size to the supply openings in the nozzle plate and are similar in shape to the supply openings. This ensures easy entry of the feed streams from the connecting feed ports. Plate (b) comprises rows of openings which divide each feed stream into four secondary streams, as in FIG 49b in 4 , while the plates (c) - (f) successively reshape each of the side streams in order to provide extended feed stream cross sections at the drains from the transition area to the discharge area.

The laxative area of the head is out one hardened Steel cover plate made of type 422 stainless steel. The surfaces this plate are ground flat and parallel and then is a row of discharge slots, which contains two rows of parallel slots in one surface of the Cut plate. The rows cross at a 90 ° angle and the slots in each row are evenly spaced between the slots of 2.5 mm. Thus, a uniform series is being launched square "pins" by means of the slots in the surface of the plate.

That to form the slots in the disk surface The method used is grinding wheel grinding. Thin grinding wheels Boron nitride are used to make the plate with slots 3.81 mm (0.15 in) depth from the plate surface. The slots are a construction with two sizes, namely a width of approx. 0.36 mm (0.014 in) on the machined surface of the plate and up to one Depth of approximately 0.89 mm (0.035 in) from the surface, and from there with a Width from about 0.18 mm (0.007 in) to over the floor area 2.92 mm (0.115 in) the slot depth.

The nozzle, transition and drain covers will be next to a preform for an extrusion head put together. The transition plates in the (a) - (f) order are on the nozzle plate piled up, being carefully aligned axially, for an exact coverage of the feed openings with all channels in the transition plates to secure. The steel cover plate is then on top of the transition plate stack positioned with the machined (slotted) surface of the Cover with the top transition plate (f) the transition area connected is. The cover is placed carefully on top of each other stacked transition plates positioned, to ensure that each slot segment in the cover becomes one of the processes the extended In addition to current channels in the top transition plate of the stack is aligned axially.

The axially aligned head components then become under heat and pressure put together, to make a whole head preform. The joining procedure used is a conventional one Diffusion contact making process in which a single NiP layer alloy is used, which leads to a thickness of approx. 5 μm on one of the two metal surfaces each to be added Layer pairs is plated. A permanent assembly of all Layers in an entire preform assembly are created by heating the stack to a maximum temperature from 1000 ° C and under a maximum pressure of 992 psi (6.84 Mpa). After assembling and cooling building a conventional one Starting cycle for 400 series steels subjected.

The assembled preform thus delivered will be next subjected to a cover plate processing step. At this step a layer of material is removed from the unprotected side of the cover, the removed layer being of sufficient thickness, around the tips of the discharge slots expose which in the opposite surface the cover have been incorporated. Wire EDM is for removal the desired one Layer of surface material applied procedures.

Finally the cover comes with unprotected Grinded and / or polished slots around the discharge surface and other foreign and interior surfaces smooth the head. If wanted, the head can then be left on and / or with one of the known durability coatings which are provided for the special application of honeycomb extrusion of interest as useful applies. Examples of known durability coatings, which are used for extrusion abrasive batch materials based on ceramic powder are contained titanium nitride, titanium carbide, titanium carbonitride, or the like Substances.

A special advantage of extrusion heads, which are put in relation to the previous example, is an extended service life, in particular for the extrusion of plastic-coated batches which contain abrasive ceramic materials consisting of fine particles. Since the feed streams forwarded to the drain region of the head can be reshaped and / or forwarded to any arbitrary position, such as e.g. B. to the surfaces with the pins or "center slot" areas of the discharge opening, pin wear can arise from the less susceptible side surfaces, rather than through the corners of the pin base surfaces. This delays the undesirable changes in the shape of the pin corners, which is the reason for Product defects, such as enlarged wall doubles areas or so-called "thick mullions".

The fact that changes the direction and shape in the feed streams relative gradually and in front of the feed stream line to the base areas the pins taking place also reduces head and pin wear and lengthens proportionally the life of the head. The feed opening / discharge slot dislocations, which due to drilling errors during the production of conventional Heads evoked become, become completely avoided and the feed current impedance is minimized because the 90 ° flux return is not longer required at the opening / slot Interfaces in such conventional behead needed becomes

Another important advantage of these head designs is the ability to reduce the feed opening size in heads with a high number of cells by using composite feed transition areas. Thus, as noted previously, the feed stream division within the transition area can be accomplished in one, two, or even more steps. In this way, a single feed opening in the head body could be divided into 3 or 4 Side streams at several merging sections in the transition area, extrudable material too 9 . 16 or feed more slit segments in the drain area of the head. Such a head is both more solid and less expensive than a conventional head with a high number of cells due to the reduced number of feed openings, and could accordingly have a reduced flow impedance of the feed opening batch and lower susceptibility to changes in the roughness of the feed opening.

After all, these heads offer one improved extrusion performance for unusual Head configurations such as B. heads with rectangular cells, using conventional ones Zuführöffnungsformen it is quite difficult to feed them uniformly. The ability to transition channels of arbitrary size, shape and number between a conventional one Zuführöffnungsreihe and a customized range of discharge slots to disposal Providing provides much improved control over the distribution of the batch material to discharge areas of such heads which creates a very flat flow front over the head discharge area and a steady growth of the material at the corners and surfaces of the Cell guaranteed becomes.

Claims (12)

A honeycomb extrusion head ( 20 ), which comprises: a feed area ( 22 ) with a variety of feed openings ( 23 ) for filling an extrudable material; a laxation area ( 26 ), which ends at a discharge surface, the discharge surface having a discharge opening ( 27 ) for discharging the extrudable material in the form of a grooved, honeycomb-shaped body; and a transition area ( 24 ), which is arranged between the feed and discharge area, characterized in that the transition area consists of a stack of at least four interconnected metal transition plates ( 25a - 25j ) is formed, with each plate having a sheet thickness of less than approx. 1 mm, and the transition area having a large number of channels or channels ( 29a . b ), which are formed by succession of openings in the transition plates, for transporting the extrudable material in the form of a feed stream between the feed and discharge area. An extrusion head according to claim 1, wherein: the feed openings ( 23 ) are parallel to a flow axis for the extrudable material; the transition area ( 24 ) comprises an inlet or filler transition plate which adjoins the feed area and an exit or discharge transition plate which adjoins the discharge area; and in an interval between the feed transition plate and the discharge transition plate, the channels (i) divide into secondary channels, (ii) have a non-parallel alignment with the flow axis; and / or (iii) change in cross section. An extrusion head according to claim 1, wherein the transition region 5–50 transition plates includes. An extrusion head according to claim 1, wherein: the discharge area ( 26 ) a series of pens ( 37a ), wherein each pin (i) is connected at an attachment end to the transition layer of the discharge surface, (ii) ends at an outside on the discharge surface, and (iii) is separated by spaces from adjacent pins, and the discharge opening is formed by the spaces ( 37 ) is formed. An extrusion head according to claim 4, wherein the pins ( 37a ) have a lower average at the fastening end than at the outer end. An extrusion head according to claim 1, wherein the majority the transition plates 5-50 plates comprises and wherein each plate has a thickness in the range of 125-500 microns. A method of extruding a honeycomb product comprising: (i) feeding an extrudable material in the form of a plurality of feed streams into a plurality of feed openings ( 23 ), which in a feed area ( 22 ) of a honeycomb extrusion head ( 20 ) run; (ii) routing the feed stream from the feed ports ( 23 ) in a multilayered over corridor area ( 24 ), which adjoins the feed area, the transition area having at least four interconnected metal transition plates ( 25a - 25j ), whereby each plate has a sheet thickness of less than approx. 1 mm and a large number of channels ( 29a . b ), which are formed by a succession of openings in the plates and are connected to the feed openings for conveying the feed streams; (iii) returning, reshaping and / or dividing the feed streams within the channels in the transition region to provide a plurality of returned, reshaped and / or split feed streams of extrudable material; (iv) forwarding the returned, split and / or reformed feed streams from the transition area ( 24 ) in a discharge area ( 26 ), which adjoins the transition area, the discharge area having a discharge opening ( 37 ) which corresponds to the channels ( 29a . b ) is connected and configured to discharge the extrudable material in the form of a grooved, honeycomb-shaped body; and (v) discharging the extrudable material from the discharge opening in the form of a honeycomb product. A method according to claim 7, wherein: the feed streams the feed ports ( 23 ) flow along a river axis and the feed streams are returned in the smallest areas of the channels, along flow paths, the direction of which deviates from the river axis. A method according to claim 8, wherein: the feed streams are divided in the channels to form separate feed streams and the separate feed streams in the discharge area ( 26 ) to get redirected. A method of manufacturing a honeycomb extrusion head ( 20 ), which comprises the following steps: formation of a plurality of feed openings ( 23 ) in a nozzle plate ( 22 ); Form a series of openings in each of at least four interconnected metal transition plates ( 25a - 25j ), each plate having a sheet thickness of less than approx. 1 mm; Stacking the transition plates to form a stack of plates, wherein the openings in each plate are at least partially overlapped with the openings of adjacent plates in the stack of plates, and wherein the arrangements of the openings are a series of grooves ( 29a . b ) form through the stack of plates; Positioning the plate stack against the nozzle plate so that the feed openings are at least partially overlapped with the grooves; Positioning a mold removal area ( 26 ) against the plate stack and connecting the nozzle plate ( 22 ) with the plate stack ( 24 ) and the mold discharge area ( 26 ) to form a preform of the extrusion head. A method according to claim 10, wherein the nozzle plate, the plate stack and the mold discharge area made of stainless steel made and by diffusion contact making be connected to each other. A method according to claim 10, wherein a plurality on transition plates 5-50 plates comprises and wherein each plate has a thickness in the range of 125-500 microns.